High strength laminate

Abstract

A high strength laminate formed by stretching together is superposed relation at least two laminates of at least two films each, which films exhibit a distinct fibrous morphology with the fibres forming a distinct generally unidirectional grain when observed on a macroscale but with the fibre-portions strongly deflected from this direction when observed on a microscale and with said unidirectional grain in at least two of the films criss-crossing each other, so as to combine such laminates which are then separated by peeling apart. The resultant separated laminates have high strength with one highly smooth surface evidenced by high gloss and a high coefficient of friction particularly suitable for the production of high quality sacks while the opposite surface is slightly corrugated in its lengthwise direction.

I claim: 
     
       1. A high-strength laminate comprising at least two generally weakly adhered biaxially oriented films, each formed of a polymer composition which exhibits a distinct fibrous morphology with the fibres forming a distinct generally unidirectional grain when observed on a macroscale but with the fibre-portions strongly deflected from this grain direction on a microscale and with said unidirectional grain in at least two of the films criss-crossing each other, characterized in that one surface of said laminate has a shallow corrugated configuration with the corrugations being generally linearly directed, while the other surface has an essentially smooth planar configuration essentially free of any microtopography. 
     
     
       2. The laminate of claim 1 wherein each such oriented film comprises a blend of high density polyethylene and low density polyethylene. 
     
     
       3. The laminate of claim 2 wherein the molecular weight of said low density polyethylene is significantly lower than that of said high density polyethylene. 
     
     
       4. The laminate of claim 3 wherein the weight ratio of said high density polyethylene to said low density polyethylene is in the range of about 15:85 to about 75:25. 
     
     
       5. The laminate of claim 1 wherein each such film further comprises polypropylene in a ratio up to about 70:30 relative to said blend. 
     
     
       6. The laminate of claim 5 wherein the molecular weight of said polypropylene is significantly lower than that of said high density polyethylene. 
     
     
       7. A laminate comprising at least two adhered biaxially oriented polymeric films, characterized in that one surface of said laminate has a shallow corrugated configuration with the corrugations being generally linearly directed, while the other surface has an essentially smooth planar configuration essentially free of any microtopography. 
     
     
       8. The laminate of claim 7 wherein at least one of said polymeric films comprises polyethylene.